A new study from the University of Wisconsin School of Medicine and Public Health has raised concerns about how thyroid cancer is being diagnosed in the United States. The research focused on papillary thyroid cancer, the most common form of the disease. It found that most cases identified over the last three decades likely did not need treatment.
This isn’t the first time experts have raised this concern. Earlier research already showed that papillary thyroid cancer often grows very slowly. In many cases, it never causes serious harm. Autopsy studies have even found that about one in ten adults carry small thyroid cancer nodules when they die. These nodules were never the cause of death.
The Wisconsin team looked at national data spanning from 1991 to 2019. Their analysis suggests that somewhere between 72% and 94% of papillary thyroid cancer cases diagnosed during this time were likely overdiagnosed. In other words, doctors found and treated cancers that probably would never have threatened the patient’s life.
Why is this overdiagnosis happening? Dr Louise Davies, a professor of otolaryngology at UW, attributes the issue primarily to advancements in imaging technology. Ultrasound scans have become much more common. These scans are effective at catching small, slow-growing cancers. But many of these cancers would likely never have caused problems if left alone.
Davies explained that even after accounting for a real rise in thyroid cancer cases, most diagnoses and treatments over the past 30 years still count as overdiagnosis. She pointed out that this comes with real costs. Patients may undergo unnecessary surgery. Some need lifelong hormone therapy afterward. Beyond the physical toll, there’s emotional stress and financial burden too.
The study also found a gender gap. Women were overdiagnosed far more often than men. Researchers estimate that between 443,000 and 574,000 women were affected over the 28-year period. For men, the number ranged from 108,000 to 155,000.
To explore possible solutions, the researchers built a mathematical model. They wanted to see what would happen if doctors cut back on ultrasounds for thyroid nodules that can’t be felt by hand during a physical exam. The results were striking. A one-third reduction in these ultrasounds could lower cancer diagnoses by 17%. A two-thirds reduction could cut diagnoses by 41%. Most importantly, these reductions barely affected death rates. The change in mortality was less than 0.1%.
Dr David Francis, another UW otolaryngology professor involved in the study, believes this points to a real opportunity. He said that even small shifts in how doctors refer patients for ultrasounds could prevent tens of thousands of unnecessary diagnoses every year. And such a change could happen without putting patients at greater risk of dying from the disease.
Francis argued that these findings could help shape better medical guidelines. Currently, there’s no clear standard for when ultrasounds should be used to check thyroid nodules. He believes a more careful, risk-based approach to care could make a big difference.
The data from the past three decades presents a compelling narrative. Thyroid cancer diagnoses in the U.S. have more than tripled since the early 1990s. Yet death rates from the disease have stayed flat. This gap between rising diagnoses and steady mortality is a strong signal that overdiagnosis, not an actual increase in dangerous cancers, is driving the trend.
Francis summed up the goal simply. He said the point isn’t to stop screening altogether. It’s to make sure patients get care that actually helps them. By using imaging more thoughtfully, doctors can still catch the cancers that matter. At the same time, they can avoid putting patients through treatments they never needed.
